The construction of such a device remains relatively simply when the two valve members are disposed at a certain distance from each other and their rotation may consequently be controlled simultaneously. On the other hand, this does not apply when it is desired to avoid any risk of the conveyed liquid coming into contact with the outside environment due to the risks of pollution which would otherwise be created; in such a case, it is necessary that, in the position in which the elements are coupled, the semi-spherical protuberance of the valve of one of the elements be housed in a conjugate depression made in the wall of the other, and it will be understood that the interpenetration of the two parts of semi-spherical profile normally opposes any simultaneous movement of rotation of the two valves thus fitted.
In order to solve the problem thus raised, it is generally provided that the rotation of the valves in the course of the longitudinal movement for coupling, be preceded by an axial displacement or recoil of at least one of the two inside the body which contains it. It will be understood that, although such previous recoil thereafter allows simultaneous rotation of the two valves of the device, it causes the liquid to come into contact with certain of the parts of said device, consequently involving relatively complicated cleaning operations if it is desired to avoid any risk of internal pollution. In addition, it should be observed that the structures proposed are complex and increase the cost of the assembly.
It is an object of the present invention to overcome these drawbacks, with the aid of a coupling device of the type incorporating rotating valve members, which avoids the formation of any interior space capable of retaining a fraction of the conveyed fluid and which may consequently be cleaned simply by passing a fluid stream, without any dismantling of parts.